Pavement marker and mounting base member

ABSTRACT

IN A PAVEMENT MARKER CAPABLE OF SERVICE IN SNOW AREAS AND HAVING A REFLECTOR FOR ESTABLISHING A MARKING VISIBLE FROM AN ONCOMING VEHICLE ON A ROADWAY SURFACE, A BASE MEMBER CONSTRUCTED FOR SECURING THE PAVEMENT MARKER TO THE ROADWAY SURFACE AND FOR PROTECTING THE REFLECTOR AGAINST DAMAGE FROM AN ONCOMING SNOWPLOW BLADE DURING SNOW PLOWING OPERATIONS, THE BASE MEMBER HAVING A BODY OF HIGH STRENGTH MATERIAL, PREFERABLY A METAL, AND INCLUDING SIDEWALLS WITH INCLINED RAMPS AT EITHER SIDE OF THE REFLECTOR FOR GUIDING AN ONCOMING SNOWPLOW BLADE OVER THE REFLECTOR WITHOUT DAMAGING CONTACT, AND SECURING SURFACES EXTENDING LONGITUDINALLY ALONG THE BODY PARALLEL TO ONE ANOTHER AND PROJECTING DOWNWARDLY INTO COMPLEMENTARY GROOVES IN THE PAVEMENT, THE SECURING SURFACES PREFERABLY LYING ON DOWNWARD EXTENSIONS OF THE SIDEWALLS AND PERPENDICULAR TO THE ROADWAY SURFACE. AUXIALIARY SURFACES MAY BE PROVIDED ADJACENT THE INCLINED RAMPS AND PARALLEL TO THE ROADWAY SURFACE FOR RESTING UPON THE ROADWAY SURFACE AND PROVIDING INCREASED RESISTANCE TO DOWNWARD MOVEMENT OF THE BODY WHEN THE INCLINED RAMPS ARE CONTACTED BY A SNOWPLOW BLADE. IN ADDITION, THE DOWNWARD EXTENSIONS MAY TERMINATE IN A SERIES OF STEPS WHICH FOLLOW A GENERALLY ARCUATE PATH SO THAT THE GROOVES IN THE PAVEMENT MAY BE ARCUATE, BUT THE STEPS WILL RESIT ROCKING MOVEMENT OF THE EXTENSIONS IN THE GROOVES.

United States Patent [72] Inventor Robert M. Flanagan Summit, NJ. [2|]Appl. No. 846,016 [22] Filed July 30.1969 [45] Patented June 28, 1971[73] Assignee Allende Esaa Corporation New York, NX. Continuation-impartof application Ser. No. 655,166, I"! 21, 1967, now abandoned and aoonthuafion-ln-part of 734,609, June 25, 1968, now abandoned.

[54] PAVEMENT MARKER AND MOUNTING BASE MEMBER l7 Claims, 12 DrawingFigs. [52] US. Cl. 94/l.5, 350/67 [51] Int. Cl. E0lc 23/16 [50] FieldofSearch 94/l .5; 350/67 [56] References Cited I UNITED STATES PATENTS2,127,037 8/1938 La Croix 94/1 .5 2,941,447 6/1960 Abbott 94/1 .5

Primary Examiner-Jacob L. Nackenoff Attorney-Samuelson and JacobABSTRACT: in a pavement marker capable of service in snow areas andhaving a reflector for establishing a marking visible from an oncomingvehicle on a roadway surface, a base member constructed for securing thepavement marker to the roadway surface and for protecting the reflectoragainst damage from an oncoming snowplow blade during snow plowingoperations, the base member having a body of high strength material,preferably a metal], and including sidewalls with inclined ramps ateither side of the reflector for guiding an oncoming snowpiow blade overthe reflector without damaging contact, and securing surfaces extendinglongitudinally along the body parallel to one another and projectingdownwardly into complementary grooves in the pavement, the securingsurfaces preferably lying on downward extensions of the sidewalls andperpendicular to the roadway surface. Auxiliary surfaces may be providedadjacent the inclined ramps and parallel to the roadway surface forresting upon the roadway surface and providing increased resistance todownward movement of the body when the inclined ramps are contacted by asnowpiow blade. in addition, the downward extensions may terminate in aseries of steps which follow a generally arcuate path so that thegrooves in the pavement may be arcuate, but the steps will resistrocking movement of the extensions in the grooves.

PATENTED JUH28 19m SHEET 5 OF 6 INVENTOR ROBERT FLHNAGHN HTTOFNIEVSPATENTEUJUNZBIQYI 0 3,587,416

SHEET 6 0r 6 J IN VEN'IOR.

ROBERT M. FLANAGAN AT TOR NE PAVEMENT MARKER AND MOUNTING BASE MEMBERThis is a continuation-in-part of applications Ser. No. 655,166, filedJuly 21, 1967, and Ser. No. 734,609, filed June 25, 1968, both nowabandoned.

The present invention relates generally to pavement markers andpertains, more specifically, to pavement markers constructed for servicein, geographical locations where weather conditions includesnow and tobase members for use in such pavement markers.

Pavement markers have become more widely accepted as permanentinstallations for marking traffic lanes and controlling the flow oftraffic on roadways in connection with or in place of conventionalpainted traffic lines. Because of their greater optical effectivenessand longer life, such markers have found wide use despite the fact thattheir initial cost has often been greater than the initial cost ofconventional painted lines.

. One factor which has limited the use of earlier pavement markers istheir inability to withstand brutal encounters with snowplow blades inareas where a significant amount of snow is likely to fall uponroadways. It would be advantageous, then, to have available a pavementmarker which could be employed successfully and economically in suchgeographical locations.

It is therefore an important object of the invention to provide apavement marker construction which can withstand the rigors of weatherand snow plowing operations in geographical areas of use where weatherconditions are a significant factor in the feasibility of pavementmarkers.

Another object of the invention is to provide a high strength pavementmarker which is relatively easy to install and will remain in placedespite brutal encounters with snowplow blades during snow plowingoperations.

A further object of the invention is to provide a pavement marker of thetype outlined above which is self-cleaning in that the reflector iscleaned by contact with the tires of oncoming vehicles.

A still further object of the invention is to provide a pavement markerof the type outlined above which includes a construction that may beinstalled in the roadway surface with a minimal excavation of thepavement.

The above objects, as well as further objects and advantages of theinvention, are attained in the invention which may be described brieflyas a mounting base member of relatively high strength material for usein a pavement marker capable of service in snow areas, the pavementmarker including a reflector for establishing a marking visible from anoncoming vehicle on the surface of the roadway, the base member beingconstructed for securing the pavement marker to the roadway and forprotecting the reflector against damage from an oncoming snowplow bladeduring snow plowing operations, the base member extending longitudinallybetween a forward portion and an opposite rearward portion and extendinglaterally between opposite side portions, the base member includingmeans forming a lower surface for fixing the base member to the roadway,a portion of the lower surface lying in a basal plane adapted to extendparallel with the roadway surface when the base member is secured to theroadway, means forming a side wall integral with the base memberadjacent to each of the side portions, the sidewalls extendinglongitudinally and upwardly with respect to the basal plane, meansforming a reflector-receiving surface integral with the lower surfaceforming means and extending laterally between the sidewalls and raisedabove the basal plane for receiving the reflector of the pavement markerwhen the reflector is secured to the mounting base member and holdingthe reflector in position above the roadway surfacewhen the mountingbase member is secured to the roadway, each sidewall including aninclined upper surface forming an inclined ramp extending from theforward portion located at an elevation corresponding approximately tothe basal plane to an uppermost portion located at an elevationcorresponding at least to the elevation of the uppermost extent of thereflector-receiving surface, the inclined ramp being locatedlongitudinally for ward of the reflector-receiving surface andmakingvanacute angle with the basal plane such that the oncomingsnowplow blade will ride up the ramp and will bedeflected from contactwith the reflector on the reflector-receiving surface as the snowplowblade passes over the pavement marker, and securing means projectingdownwardly with respect to the basal plane and forming a plurality oflower surface portionsextending generally perpendicular to the lateralextent of the base member and parallel to the longitudinal extend of thebase member for adhesively securing the base member within complementarylongitudinal grooves in the roadway against shear forces along the lowersurface portions arising out of contact between the oncoming snowplowblade and the pavement marker. The side members may include laterallyopposite side portions extending laterally away from one anotheradjacent each inclined ramp for establishing auxiliary surfaces lyingwithin the basal plane below at least a portion of each inclined rampfor resting upon the pavement. In addition, the securing means mayproject downwardly in a plurality of steps, each step having a pair ofsurfaces generally perpendicular to the lower surface portions with oneof the pair of surfaces being parallel to the basal plane while theother of the pair of surfaces is perpendicular to the basal planlegthesteps generally following an arcuate path extending downwardly fromadjacent the forward portion to adjacent the opposite rearward portionof the base member.

The invention will be more fully understood and further objects andadvantages thereof will become apparent in the following detaileddescription of embodiments of the invention illustrated in theaccompanying drawing,in which:

FIG. I is a perspective view of a pavement marker employing theinvention;

FIG. 2 is a front elevational view of the pavement marker of FIG. 1installed upon a roadway;

FIG. 3 is a longitudinal cross-sectional view taken along line 3-3 ofFIG. 2;

FIG. 4 is a diagrammatic plan view of the installed pavement markerillustratinga snowplow blade during snow plowing operations;

FIG. 5 is a perspective view of a base member and separate reflectorbefore assembly into another pavement marker;

FIG. 6 is a longitudinal cross-sectional view of still another pavementmarker illustrating another embodiment of the invention;

FIG. 7 is a perspective view of another pavement marker illustratingstill another embodiment of the invention;

FIG. 8 is a front elevational view of the pavement marker of FIG. 7installed upon a roadway;

FIG. 9 is a perspective view of another pavement marker illustrating afurther embodiment of the invention;

FIG. 10 is a longitudinal cross-sectional view of the pavement marker ofFIG. 9 installed upon a roadway;

FIG. 11 is a perspective view of still another pavement markerillustrating a still further embodiment of the invention; and

FIG. 12 is a longitudinal cross-sectional view of the pavement marker ofFIG. 11 installed upon a roadway.

Referring now to the drawing, and especially to FIGS. 1, 2 and 3, apavement marker employing the invention is illustrated at 10 and is seento have a mounting base member 12 made of metal or some other suitablerelatively high strength material. The body of the base member-.12extends longitudinally from a forward portion 14 to an opposite rearwardportion 16 and laterally between opposite sidewalls I8 spaced apart byan interconnecting web 19.

As best seen in FIGS. 2 and 3, pavement marker 10 is adapted to beinstalled upon a roadway 20 and base member 12 has a basal plane 22which extends parallel with the surface of roadway 20 when the lowersurface of the base member is affixed to the roadway surface.

The sidewalls 18 of the base member are provided with securing means inthe form of depending ribs 24 which project downwardly below the basalplane 22 and extend longitudinally to establish lower surface portionsin the form of vertical surfaces 26 extending in planes generallyperpendicular to the basal plane 22 and parallel to one anotherlongitudinally along the body of the base member 12. Ribs 24 are engagedwith complementary grooves 28 in the roadway to affix the pavementmarker to the roadway surface, preferably through the use of an adhesive29. The additional area gained by the vertical surfaces 26 of thelongitudinal ribs 24 provides the additional resistance to shear forcesplaced upon the pavement marker 10 when the marker is contacted by asnowplow blade to prevent the marker from being torn from the roadwaysurface. It has been found that the holding power of an adhesive placedalongthe vertical surfaces is much greater than the holding power of thesame adhesive placed on horizontal surfaces since the adhesive canapparently withstand greater forces in shear than in tension. Hence, theparallel longitudinal ribs 24 provide easily fabricated means forsecuring the pavement marker to a roadway surface.

In addition, the parallel ribs 24 make available a simplified method andprocedure for installing a well-secured pavement marker upon a roadwaysurface by requiring only the provision of parallel grooves 28 in thepavement. Such parallel grooves may be cut in the pavementsimultaneously and effectively with standard circular saws mounted on acommon arbor which would extend transverse to the roadway and travelalong the roadway to be run into the pavement periodically,corresponding with the spacing between adjacent pavement markersinstalled in a line. Once the grooves 28 are cut, it is a relativelysimple matter to place the pavement marker on the roadway surface withthe ribs 24 inserted within the grooves 28. Thus, the pavement marker isinstalled without the necessity for excavating the roadway surface.

Pavement marker-l0 includes a reflector 30 which is afiixed to areflector-receiving surface in the form of a front face 31 of anupstanding portion 32 of the body of the base member 12 by means of anadhesive 33 and faces forward in order to receive incident light fromoncoming vehicles and reflect such light to establish a marking visibleat night. The reflector 30 is constructed so as to also provide surfacesfor specularly reflecting ambient daylight to establish a markingvisible 7 under daytime conditions as well as the marking visible onlyat night. The reflector 30 is raised above the surface of the roadway inorder to provide a marking which may be effectively viewed at reasonableviewing distances. Additionally, the reflector 30 is advantageouslyplaced at an acute angle to the roadway surface sov-that the face of thereflector will be cleaned by wiping contact with the tires of oncomingvehicles. Although a wide variety of reflectors may be employed inconnection with base member 12, the illustrated reflector 30 is aretrodirective reflector of the cube-comer type which is constructed ofa light-transmitting synthetic resin, such a methyl methacrylate, andwhich is affixed to the outer surface of upstanding portion 32 of thebase member by an adhesive or like means. Such a reflector, as well asalmost any other reflector, must be protected from contract with asnowplow blade during snow plowing operations since such contact couldeither mutilate the reflector or peel the reflector from the base memberand thus render the pavement marker inoperable.

In order to protect the reflector 30 from being gouged or stripped fromthe base member 12 by an oncoming snowplow 22, the uppermost portions 38establishing a path for a snowplow blade which will ensure that thesnowplow blade will completely avoid contact with the reflector'30.

1 As best seen in FIG. 4, during snow plowing operations'it is likelythat only the corner 40 of a snowplow blade 42 will usually contact thepavement marker 10 since the pavement marker will delineate a trafficlane and ordinary snow plowing operations call for the plowing of onelane at atime. Additionally, although it is desirable to space thesidewalls l8 apart a distance great enough to admit the tires ofoncoming vehicles between the sidewalls for the purpose of permittingcontact between the tires and the reflector so that the tires will wipethe reflector clean, such a measure increases the chance that the comer40 of the oncoming snowplow blade 42 will fall between the sidewalls 18with the blade riding upon only one sidewall, as seen in FIG. 4. Becausesnowplow blades are generally set at an angle to the direction of travelof the blades and since the comer of a snowplow blade is very likely tofall between the sidewalls of the pavement marker, it will be seen thatthe point or comer 40 of the snowplow blade 42 will arrive at thereflector 30 ahead of the portion 44 of the blade which contacts andrides upon the inclined ramp 36. Thus, unless the elevation of theportion 44 of the blade which rides upon the sidewall 18 is great enoughto raise the comer 40 of the blade above the uppermost edge 34 of thereflector 30, the reflector will be gouged or even destroyed by contactwith the comer of the snowplow blade. However, by providing the flatuppermost portions 38 with a longitudinal length great enough to assurethat portion 44 of the blade 42 is raised to an elevation sufficient toraise the comer 40 of the blade above the upper edge of the reflectorprior to the arrival of the corner of the blade inthe vicinity of theupstanding portion 32 of the base member 12, contact between the cornerof the blade and the reflector is precluded.

The inclined ramps 36 make an acute angle A with the basal plane 22 (seeFIG. 3). Angle A is best held to a minimum in order to reduce the forcesgenerated by contact between the traveling snowplow blade 42 and thebase member 12 of the pavement marker 10. Additionally, an angle A oflarge magnitude would cause the snowplow blade to hop with concomitantill effects on the roadway surface as well as on the blade. On the otherhand, an exceptionally small angle A would require an inordinately longbase member 12 in order to attain blade, the reflector is placed betweenthe sidewalls 18 with the uppermost edge 34 of the reflector 30 nohigher than the upblade will ride up the inclined ramps 36 and-thus bedeflected away from the reflector.

It is noted that each sidewall 18 includes an uppermost portion 38 whichis generally flat and parallel to the basal plane the necessaryelevation. It has been found that for most snow plowing operations atspeeds well below 40 miles per hour angle A may be approximately 5 to15. For high-speed snow plowing operations, in the vicinity of 40 to 45miles per hour, an angle A of about 8% has been found preferable.

The base member must be fabricated of a material strong enough towithstand contact with the snowplow blade. It has been found that basemembers fabn'cated of pearlitic ductile iron are well suited towithstanding the shock of contact with a snowplow blade and are ruggedenough to remain serviceable over a long period of time without beingworn away by contact with oncoming traffic including snowplow blades. Inthe illustrated embodiments, the body of the base member has beensuccessfully fabricated in the form of a unitary casting of ductileiron, such as pearlitic ductile iron (ASTM A536-65T or ferritic nodulariron(ASTM A53667 which was then heat treated to obtain a core hardnessof about 26 to '34 Rockwell C and the sidewalls,-especially in thevicinity of the inclined ramps, were hardened, either by induction orflaming hardening. To a surface hardness of about 50 to 55 RockwellC'for a depth of about 0.050 to 0.100 inch. The above core hardnessprovides the toughness necessary to withstand brutal encounteam withsnowplow blades while the surface hardness is great enough to withstandthe abrasion of the snowplow blade as it passes over the sidewalls.

A second reflector 50 may be affixed to the rear face 52 of theupstanding portion 32 of the base member 12 to establish a bidirectionalpavement marker. Since the second reflector 50 is bounded on both sidesby extensions 54 of the sidewalls 18, a snowplow blade will not comeinto contact with the second reflector body as the blade returns to theroadway surface 20 from the uppermost portion 38 of the sidewalls.

It is noted that the vertical surfaces of each sidewall 18 are inclinedtoward one another in the upward direction (see FIG. 2). The inclinationof the exterior surfaces 56 of the sidewalls 18 reduces the shock uponthe tires of oncoming vehicles should these tires strike the outersurfaces of the sidewalls. The inclination of the interior surfaces 58of the sidewalls 18 facilitates the engagement and contact of the tiresof the oncoming vehicles with the outer surface of the reflector 30 sothat the reflector is wiped clean by contact with the tires.

Turning now to the embodiment illustrated in FIG. 5, a pavement marker110 is shown assembled of various component parts. Thus, the base member112 is fabricated from separate sidewalls 114 which are welded to a web116 along weld lines 118 to establish an integral structure. As in theembodiment described above in connection with pavement marker 10, eachsidewall 114 is provided with a depending longitudinally extending rib120 for securing the base member 1 12 within complementary grooves in aroadway surface.

The web 116 provides a platform 122 between the sidewalls 114, uponwhich platform may be located a reflector unit 124, in this instance amolded plastic reflector unit which is to be secured to the platformwith an adhesive 125. The height of the reflector unit 124 does notexceed the height of the sidewalls 114 so that the top 126 of thereflector unit will not project above the uppennost portion 128 of eachsidewall. As in pavement marker 10, the sidewalls 114 are each providedwith an inclined ramp 130 leading to the flat uppermost portion 128 andthe flat uppermost portions 128 are of sufficient length to assure thatthe pointed corner of a snowplow blade will not contact the reflectorunit 124.

The welded construction of base member 112 permits the use of differentmaterials for the sidewalls and the web and allows a wider latitude inthe choice of specific materials tailored for withstanding theparticular conditions encountered by individual component parts.Additionally, a wider latitude in the construction of the reflector unitis permitted by merely providing a flat web 116 to which may be affixedany one of a number of possible reflector units.

Referring now to FIG. 6, still another embodiment of the invention isshown in the form of pavement marker 210 which is constructed in amanner similar to pavement marker 110 in that the base member 212 hassimilar sidewalls 214 (only one of which is illustrated) joined togetherby a connecting web 216. Each sidewall 214 has a longitudinal rib 218projecting downwardly below the basal plane 220 for securing thepavement marker 210 upon the surface of a roadway.

A reflector unit 222 is secured to the platform 224 of the web 216 by anadhesive 225. In this instance, the reflector unit 222 is a shell 226molded of light-transmitting synthetic resin and filled with areinforcing material, such as an epoxy resin, which serves as a core 228for reinforcing the shell 226. The reflector unit 222 is bidirectionalin that a retrodirective reflector 230 is molded into each face-232 ofthe reflector unit 222.

Pavement marlter 210 is particularly suited to locations where asnowplow may approach the marker from either direction, such as where aseries of such markers define a centerline in a roadway having only onetraffic lane in either direction. Thus, sidewalls 214 are each providedwith an upperrnost portion 234 which is not only above the top 236 ofthe reflector unit 222, but which extends beyond the reflector unit 222in each direction for a sufficient length to assure that a snowplowblade which will ride up either inclined ramp 238 will avoid contactwith the reflector unit 222. The inclined ramps 238 are located adjacenttheforward portion and the rearward portion of each sidewall 214 and areinclined. in opposite directions, but at similar acute angles with thebasal plane 220 so that pavement marker 210 is rendered bidirectionalnot only from the standpoint of reflecting incident light from eitherdirection, but from the standpoint of withstanding contact with snowplowblades traveling in either direction along the roadway.

It has been found that when a snowplow blade contacts, the inclinedramps of the body of a pavement marker=as described above, there is atendency for the body of the marker to move downwardly into the pavementupon which the marker is installed as a result of the forces applied bythe snowplow blade. The embodiment of FIGS. 7 and 8 incorporates meansfor precluding such movement and shows a pavement marker 310 having abase member 312 extending longitudinally from a forward portion 314 to arearward portion 316 and including laterally spaced sidewalls 318interconnected by a web 319.

Pavement marker 310 may be installed upon a roadway surface 320 and hasa basal plane 322 which will extend parallel to the roadway surface whenso installed. As in the earlierdescribed embodiments, pavement marker310 includes downwardly depending parallel ribs 324 which providevertical securing surfaces 326 which are adhered to the surfaces ofgrooves 328 in the pavement by means of an adhesive 329.

A reflector 330 is affixed to the base member between the sidewalls 318and is protected from oncoming snowplow blades by inclined ramps 336 asdescribed above.

In order to preclude downward movement of the base member 312 in thevicinity of inclined ramps 336' when a snowplow blade contacts and ridesup the ramps, the sidewalls 318 are provided with laterally oppositesidewall portions 340 which extend laterally outwardly and away from oneanother adjacent the forward portion of the body of the pavement markerbase and adjacent the inclined ramps. These sidewall portions 340establish auxiliary lower surfaces 342 lying in the basal plane 322 sothat an increased horizontal surface area is presented to the pavementadjacent the forwardportion of the body thereby providing addedresistance to downward movement. Thus, the laterally extending sidewallportions 340 serve as sponsonlike structures for maintaining the correctposition of the pavement marker upon the roadway surface.

Turning now to FIGS. 9 and 10, there is illustrated a pavement marker410 having a base member 412 very similar to that of earlier describedembodiments in that the base member extends from a forward pontion 414to a rearward portion 416 and includes laterally spaced sidewalls 418interconnected by a web 419. I

The pavement marker 410 is shown, in FIG. 10, installed upon a roadwaysurface 420 and has a basal plane 422 which extends parallel to theroadway surface when so installed.

In pavement marker 410, the downwardly depending ribs 424 are providedwith a radius of curvature 425 which increases the surface area ofvertical securing surfaces 426 and which matches the radius of curvatureof a circular saw blade (not shown) that is employed to cut the grooves428 into which the ribs 424 are placed during installation of thepavement marker. Thus, the saw blade may be rotated and drivendownwardly into the pavement to cut an arcuate slot and then raisedagain to leave behind the arcuate groove 428. No longitudinaltranslation of the saw' blade is required and the grooves 428 arecompletely filled by the arcuate ribs 424. This installation procedureis much simplified and the increased area of vertical securing surfaces426 provides even greater holding power for the adhesive 429.

As in the earlier-described embodiment of FIGS. 7 and 8, pavement marker410 has a least a forward reflector 430 lying between the sidewalls 418and is provided with inclined ramps 436 adjacent which are sponsonlikesidewall portions 440 providing auxiliary lower surfaces 442 ofincreased area lying in the basal plane 422 below at least a portion ofeach inclined ramp 436.

Referring now to FIGS. 11 and 12, a still further embodiment of theinvention is shown in the form of pavement marker 510 having a basemember 512 very similar to that of the earlier-described embodiments inthat the base member extends from a forward portion 514 to a rearwardportion 516 and includes laterally spaced sidewalls 518 interconnectedby web 519. a

The pavement marker 510 is shown, in FIG. 12, installed upon aroadwaysurface 520 and has a basal plane 522 which extends parallel to theroadway surface when so installed.

ln pavement marker 510, downwardly depending ribs 524 are provided withvertical securing surfaces 526 which cooperate with grooves 528 intowhich the ribs 524 are placed during installation of the pavement markeras described in connection with the earlier embodiments. The grooves 528each have a radius of curvature which matches the radius of curvature ofa circular saw blade (not shown) that is employed to cut an arcuate slotand then raised again to leave behind the arcuate groove 528. Nolongitudinal translation of the saw blade is required. Hence, as in theembodiment of FIGS. 9 and 10, the installation procedure is muchsimplified and the increased area of vertical securing surfaces 526provides an even greater holding power for the adhesive 529.

As in the earlier described embodiment of FIGS. 7 and 8, pavement marker510 has at least a forward reflector 530 lying between the sidewalls 518and is provided with inclined ramps 536 adjacent which are sponsonlikesidewall portions 540 providing auxiliary lower surfaces 542 ofincreased area lying in the basal plane 522 below at least a portion ofeach inclined ramp 536.

In view of the arcuate configuration of grooves 528 there may be atendency for the base member 512 to rotate in a counterclockwisedirection when the inclined ramps 536 are struck by an oncoming snowplowblade. in order to defeat such a tendency, the downwardly depending ribs524 are provided with a plurality of steps 550 which generally follow anarcuate path so as to be confined within an arcuate boundary and permitthe downwardly depending ribs 524 to follow generally the arcuatecontour of the arcuate grooves 528, but provide locking surfaces 552 and554 which deviate from the arcuate configuration and cooperate withadhesive 529 which fills the voids between the arcuate groove 528 andthe steps 550 to prevent suchunwanted rotation of the base member 512.Thus, although downwardly dependent ribs 524 follow generally a radiusof curvature extending from adjacent the forward portion 514 to adjacentthe rearward portion 516, the steps 550 each provide a pair of lockingsurfaces which extend generally perpendicular to the vertical securingsurfaces 526. One of the pair is a locking surface 552 which isgenerally parallel to the basal plane 522 and the other of the pair is alocking surface 554 which is generally perpendicular to the basal plane.The pavement marker 510 thus attains all the advantages of thesimplified installation procedure resulting from the use of a circularsaw blade and the increased surface area of vertical securing surfaces526 resulting from the contour of the downwardly depending ribs 524while being locked even more securely in place upon the roadway surface.

it is to be understood that the above detailed description of preferredembodiments of the invention are provided by way of example onlyjVariousdetails of design and construction may be modified without departingfrom the true spirit and scope of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

lclaim: l. A mounting base member of relatively high strength materialfor use in a pavement marker capable of service in snow areas, thepavement marker including a reflector for establishing a marking visiblefrom an oncoming vehicle on the surface of a roadway, said base memberbeing constructed for securing the pavement marker to the roadway andfor protecting the reflector against damage from an oncoming snowplowblade during snow plowing operations, said base member extendinglongitudinally between a forward portion and an opposite rearwardportion and extending laterally between opposite side portions, saidbase member including:

means forming a lower surface for affixing the base member to theroadway, a portion of-said lower surface lying in a basal plane adaptedto extend parallel with the roadway surface when the base member issecured to the roadway;

means forming a sidewall integral with the base member adjacent each ofsaid side portions, said sidewalls extending longitudinally and upwardlywith respect to the basal plane;

means forming a reflector-receiving surface integralwithsaid lowersurface forming means and extending laterally between the sidewalls andraised above said basal plane for receiving the reflector of thepavement marker when the reflector is secured to the mounting basemember and holding the reflector in position above the roadway surfacewhen the mounting base member is secured to the roadway;

each sidewall including an inclined upper surface forming an inclinedramp extending from said forward portion located at an elevationcorresponding approximately to said basal plane to an uppermost portionlocated at an elevation corresponding at least to the elevation of theuppermost extent of the reflector-receiving surface, the inclined rampbeing located longitudinally forward of the reflector-receiving surfaceand making an acute angle with the basal plane such that the oncomingsnowplow blade will ride up the ramp and be deflected from contact withthe reflector on the reflector-receiving surface as the snowplow bladepasses over the pavement marker; and

securing means projecting downwardly with respect to the basal plane andforming a plurality of lower surface portions extending generallyperpendicular to the lateral extent of the base member and parallel tothe longitudinal extent of the base member for adhesively securing saidbase member within complementary longitudinal grooves in the roadwayagainst shear forces along the lower surface portions arising out ofcontact between the oncoming snowplow blade and the pavement marker.

2. The base member of claim 1 wherein:

the sidewalls are spaced apart for permitting a tire of an oncomingvehicle to fall between the sidewalls and contact the reflector; and

the uppermost portion of each sidewall extends generally parallel to thebasal plane, and the top of the inclined ramp is located forward of theuppermost extent of the reflector-receiving surface for extending saiduppermost portion forward of the reflector-receiving surface a distancegreat enough to assure that all portions of the oncoming snowplow bladewill avoid contact with the reflector.

3. The base member of claim 1 wherein said securing means includes atleast two ribs projecting downwardly below the basal plane for beingembedded in the complementary grooves of the roadway and extendinglongitudinally to form said lower surface portions.

4. The base member of claim 3 wherein the ribs follow a generallyarcuate path from adjacent the forward portion to adjacent the oppositerearward portion of the base member and include a plurality of stepseach providing locking surfaces which deviate from the arcuate path.

5. The base member of claim 4 wherein each said step includes a pair ofsaid locking surfaces extending generally perpendicular to the lowersurface portions of the securing means, one of said pair of lockingsurfaces extending generally parallel to the basal plane and the otherof said pair of locking surfaces extending perpendicular to said basalplane.

6. The base member of claim 1 including laterally opposite sidewallportions extending laterally away from one another adjacent to theforward portion of the base member establishing auxiliary lower surfacesof increased area lying in said basal plane adjacent the forward portionof the base member for resting upon the roadway surface when the basemember is affixed to the roadway and providing added resistance todownward movement of the forward portion of the base member when theoncoming snowplow blade rides up the ramps.

7. The base member of claim 1 wherein the acute angle between theinclined ramp and the basal plane is approximately 5 to 15.

8. The base member of claim 1 wherein the acute angle between theinclined ramp and the basal plane is about 8.5".

9. The base member of claim l wherein each sidewall includes a furtherinclined ramp extending between the rearward portion of the base memberat an elevation corresponding to the level ofthe roadway surface whenthe base member is affixed to the roadway. and said uppermost portion ofthe base member. said further inclined ramp making an acute angle withthe basal plane similar to the acute angle made by the inclined rampbetween the forward portion of the base member and the uppermostportion.

10. The base member of claim 1 wherein the high strength material is ametal tough enough to withstand the shock of contact with an oncomingsnowplow blade and hard enough to withstand the abrasion of the snowplowblade as it passes over the sidewalls.

1]. The base member of claim 1 wherein the high strength material isductile iron having a core hardness of about 26 to 34 Rockwell C and asurface hardness of about 50 to 55 Rockwell C.

12. A base member for a pavement marker which includes a reflector. thebase member comprising: 7

at least two longitudinal side members spaced laterally from oneanother; I a web interconnecting said side members and having at least alower portion thereoflying in a basal plane; 1

means forming a reflector-receiving surface integral with said web andextending laterally between said side mem bers for receiving thereflector of the pavement marker when the reflector is secured to thebase member;

said side members each having a sidewall rising above the basal planeand including an inclined upper surface portion forming an inclined rampextending in a direction from one end toward the other end ofa sidemember and rising at an acute angle to the basal plane from the basalplane to the uppermost portion of the sidewall, said uppermost portionbeing at an elevation corresponding at least to the elevation of theuppermost extent of the reflector-receiving surface. each sidewallextending below the basal plane and including longitudinally extendingparallel surfaces projecting below the basal plane and perpendicularthereto for being embedded in the pavement.

13. The pavement marker base member of claim 12 wherein said sidemembers include laterally opposite side portions extending laterallyaway from one another adjacent each said inclined ramp and providingauxiliary surfaces lying Within the basal plane below at least a portionof each said inclined ramp for resting upon the pavement.

14. The pavement marker base member of claim 12 wherein each sidewallextends below the basal plane to a generally arcuate boundary extendingfrom adjacent one end to adjacent the other end of the side member andincluding a plurality of steps providing locking surfaces which deviatefrom the arcuate boundary.

15. The pavement marker base member of claim 14 wherein each of saidsteps includes a pair of said locking surfaces, one of said pairextending parallel to the basal plane and the other of said pairextending generally perpendicular to said basal plane. 7

16. A pavement marker employing the base member of claim 12 andincluding:

a reflector affixed to the reflector-receiving surface between theuppermost portions of the sidewalls and ris ing above the basal plane toa level no higher than the 11pperrnost portion of each sidewall, saidreflector facing toward one of the ends of a side member.

17. The pavement marker of claim 16 wherein:

the side members are spaced apart laterally for permitting a tire of anoncoming vehicle on the pavement to contact the reflector when thepavement marker is installed; and

the uppermost portion of each sidewall extends generally parallel to thebasal plane and the top of the inclined ramp is located forward of theuppermost extent of the reflector for extending each said uppermostportion forward of the reflector a distance great enough to assure thatall portions of the oncoming snowplow blade will avoid contact with thereflector.

